stress analysis of a lifting lug

[Anonymous]

Good Morning.



I am performing some analysis on a lug that will lift a 1000kg liner. The liner will be lifted by using the 28mm hole in the lug. As the liner will have to be upended fist the resulting forces will act in the X, Y and Z directions.

Do I do three different analysis for the lug in the X Y Z DIRECTIONS or can I just use the use "COMPONENTS FEATURE” to add a 10000N in each of the Fx Fy Fz directions. If I use the "COMPONENTS FEATURE" to add the 10000N in all directions will this result in an overall 30000N load. I have tried both and get different results for the maximum stress in the material. I have attached a copy of the lug.



Thanks, Paul

[Anonymous]

Good Morning.



I am performing some analysis on a lug that will lift a 1000kg liner. The liner will be lifted by using the 28mm hole in the lug. As the liner will have to be upended fist the resulting forces will act in the X, Y and Z directions.

Do I do three different analysis for the lug in the X Y Z DIRECTIONS or can I just use the use "COMPONENTS FEATURE” to add a 10000N in each of the Fx Fy Fz directions. If I use the "COMPONENTS FEATURE" to add the 10000N in all directions will this result in an overall 30000N load. I have tried both and get different results for the maximum stress in the material. I have attached a copy of the lug.



Thanks, Paul

[Anonymous]

DONT THINK THE WORD DOC WILL WORK TRY THIS

[Anonymous]

DONT THINK THE WORD DOC WILL WORK TRY THIS

[Anonymous]

Paul,

The part you initially attached shows a force being applied to the entire surface of the hole in the lug. Because you are not using Dynamic Simulation you will need to pick a couple of liner/lug lifting positions and then add the force to the lug based on the statics, which you can calculate from the geometry of your situation. To add the force you will need to split the face of the lug hole to get the fastener "contact area" and apply your load to the split face.

Without a more detailed description of the liner and how the liner and the lug are related I can't help out much more than that.

Regards,

Nathan

[Anonymous]

Paul,

The part you initially attached shows a force being applied to the entire surface of the hole in the lug. Because you are not using Dynamic Simulation you will need to pick a couple of liner/lug lifting positions and then add the force to the lug based on the statics, which you can calculate from the geometry of your situation. To add the force you will need to split the face of the lug hole to get the fastener "contact area" and apply your load to the split face.

Without a more detailed description of the liner and how the liner and the lug are related I can't help out much more than that.

Regards,

Nathan

[Anonymous]

"If I use the "COMPONENTS FEATURE" to add the 10000N in all directions will this result in an overall 30000N load."



I don't think so. Forces are vectors, so three principle vectors with magnitude of 10000 yield an equivalent of ~17320 magnitude vector, not a 30000 magnitude vector. (I'm surprised no one commented on this. BTW, unconstrained sketches have no effect on the results of the FEA as long as your solid is the desired size and shape.)



I can't remember, but does IV11 have a "bearing load" option? I believe this is probably the best choice (in combination w/ the fixed constraint you already have in place). See attached for a simulation of a couple of simple cases. Although the bearing load won't allow for axial loading of the hole, so another force will need to be added to the side face. (I believe the force is applied over the whole face and is equivalent to placing the load at the centroid)



You will need to define different simulations for different loading conditions. Unfortunately, IV only allows you to define one simulation at a time and doesn't allow you to save different loading conditions. So you will spend alot of time redefining different loading conditions and running the simulation, especially if your iterating a design. (maybe this has changed in IV2010, I certainly hope so). Like others have said, the FEA analysis is a static analysis. You can either use Dynamic Simulation to determine the loads at each time period, or estimate worst case loading and use that force.



Just from looking at the part, I believe the worst case scenario would be a bending about the long dimension of the bottom face. It will probably be the weld in tension that fails before ripping of the material. For this, I would get the Machinery Handbook and look at cantilever beams for analysis methods. Also look at the weld analysis. If you look at the reports I attached, it also suggests the same.



Remember, that while you are using IV Professional, it is using FEA Light, so be critical of your results and compare with other solution methods. Don't just assume they are correct.

[Anonymous]

"If I use the "COMPONENTS FEATURE" to add the 10000N in all directions will this result in an overall 30000N load."



I don't think so. Forces are vectors, so three principle vectors with magnitude of 10000 yield an equivalent of ~17320 magnitude vector, not a 30000 magnitude vector. (I'm surprised no one commented on this. BTW, unconstrained sketches have no effect on the results of the FEA as long as your solid is the desired size and shape.)



I can't remember, but does IV11 have a "bearing load" option? I believe this is probably the best choice (in combination w/ the fixed constraint you already have in place). See attached for a simulation of a couple of simple cases. Although the bearing load won't allow for axial loading of the hole, so another force will need to be added to the side face. (I believe the force is applied over the whole face and is equivalent to placing the load at the centroid)



You will need to define different simulations for different loading conditions. Unfortunately, IV only allows you to define one simulation at a time and doesn't allow you to save different loading conditions. So you will spend alot of time redefining different loading conditions and running the simulation, especially if your iterating a design. (maybe this has changed in IV2010, I certainly hope so). Like others have said, the FEA analysis is a static analysis. You can either use Dynamic Simulation to determine the loads at each time period, or estimate worst case loading and use that force.



Just from looking at the part, I believe the worst case scenario would be a bending about the long dimension of the bottom face. It will probably be the weld in tension that fails before ripping of the material. For this, I would get the Machinery Handbook and look at cantilever beams for analysis methods. Also look at the weld analysis. If you look at the reports I attached, it also suggests the same.



Remember, that while you are using IV Professional, it is using FEA Light, so be critical of your results and compare with other solution methods. Don't just assume they are correct.

[Anonymous]

Also, note that the reports I attached are for demonstration of methods only and should not be considered valid calculations.

[Anonymous]

Also, note that the reports I attached are for demonstration of methods only and should not be considered valid calculations.

[Anonymous]

Josh thanks for the explanations and time and everyone else that contributed. Things are a lot clearer now the way INVENTOR interacts. I think I'll just stick to hand calculations in the future and use the software to validate my results.

Cheers, Paul

[Anonymous]

Josh thanks for the explanations and time and everyone else that contributed. Things are a lot clearer now the way INVENTOR interacts. I think I'll just stick to hand calculations in the future and use the software to validate my results.

Cheers, Paul

[Anonymous]

Josh,

Just a quick one.

I have attached another scenario. A shackle is put through the lug and a force is acting only in the area of the split face in the model.

1. Is this the correct way to analyse the situation?
2. As I have split the face does the analysis take into the consideration the whole lug or just the split face?

I just want to make sure that by splitting the face I don’t split the part into several components. All I want to achieve in this scenario is to move the centre of the force to a new area where the shackle would act.

Cheers, Paul

[Anonymous]

Josh,

Just a quick one.

I have attached another scenario. A shackle is put through the lug and a force is acting only in the area of the split face in the model.

1. Is this the correct way to analyse the situation?
2. As I have split the face does the analysis take into the consideration the whole lug or just the split face?

I just want to make sure that by splitting the face I don’t split the part into several components. All I want to achieve in this scenario is to move the centre of the force to a new area where the shackle would act.

Cheers, Paul

[cadman777]

maybe you need 3 dims
i.e., add one that goes from the flat back of the eye to the circle
... chris

[cadman777]

maybe you need 3 dims
i.e., add one that goes from the flat back of the eye to the circle
... chris